Seth Azemi was declared brain dead after suffering 2 fractures to his skull.

STATEN ISLAND, N.Y. -- The city and the agency tasked with protecting children from abuse and neglect were responsible for his toddler's death, allegedly at another man's hands 15 months ago in New Brighton, claims a grieving father.

Agim Azemi, of Brooklyn, has sued the city and the Administration for Children's Services over the death of his 14-month-old son, Seth Azemi. The tot was found gravely injured, with head fractures, on Oct. 7, 2011, while in the care of his mother's then-boyfriend, Joshua Guzman, in the apartment where they resided, allege court papers.

The toddler succumbed to his injuries five days later, said authorities. Guzman was subsequently charged with murder. He has denied the allegations and awaits trial in state Supreme Court, St. George.

The civil suit, also filed in state Supreme Court, St. George, alleges the city and Children's Services failed to "properly assess and evaluate" the little boy's living conditions, and that Guzman, who was minding him, was unsuitable to care for him.

The action seeks unspecified monetary damages.

In a brief telephone conversation, Azemi's lawyer, Efrom Gross, said Children's Services had been "watching over" the family, but he did not elaborate on how or why the agency became involved.

According to its website, the agency investigates reported cases of suspected child abuse or neglect and provides "neighborhood-based services to help ensure children grow up in safe, permanent homes with strong families."

Seth lived with his mother, Stephanie Soto, then 25, his siblings, and Guzman, according to Advance reports and court papers.

The toddler was found unconscious and unresponsive in a basement apartment on Butler Terrace at 8:30 a.m. on Oct. 7, 2011, state court filings in the criminal case.

Police say Guzman was baby-sitting Seth when he swung around and hit the child's head against a bedroom wall. Guzman, then 18, admitted he was in "exclusive care" of Seth when the incident occurred, court documents said.

The toddler suffered head fractures and died on Oct. 12, 2011, after being taken off life support, said authorities.

The little boy died from a "shortage of oxygen to the brain due to whiplash shaking and blunt-force impact," said Ellen Borakove, a spokeswoman for the medical examiner's office.

Initially, the medical examiner's office found two fractures of the toddler's head. Guzman said they occurred when the boy's head and torso hit a bedroom wall, then a wooden door, after he picked him up and ran out of the room when he found the child unconscious, said court papers filed in the criminal case.

A Children's Services spokesman on Friday referred all inquiries to the city Law Department.

A Law Department spokeswoman said the civil filing had not been received. She added the city will consult with Children's Services once those documents are in hand.